Fine-particle classification apparatus and functional material production apparatus

ABSTRACT

In the fine-particle classification apparatus of the present invention, a carrier gas velocity in a take-in section to introduce the aerosol to the fine-particle classification apparatus from the aerosol generation apparatus is increased so as to decrease the static pressure in the take-in section. It is thereby possible to decrease the static pressure in the take-in section than the total pressure in the aerosol generation apparatus. As a result, it is possible to introduce the aerosol inside the fine-particle classification apparatus with a total pressure equal to or higher than that in the aerosol generation apparatus from a fine particle generating area, i.e. aerosol generation apparatus with a pressure equal to or lower than that in the fine-particle classification apparatus.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fine-particle classificationapparatus for classifying fine particles in an aerosol in a gas phase,and more particularly, to a fine-particle classification apparatus forcharging target fine particles in the aerosol and further applying anelectrostatic field to the particles, thereby classifying the particlesusing a difference between each mobility which depends on the particlediameter.

2. Description of the Related Art

As a system for fine-particle classification apparatus for classifyingfine particles in an aerosol, there have been a variety of typesconventionally. The following describes about the Differential MobilityAnalyzing (hereinafter referred to as DMA) which is the firstconventional example for the fine-particle classification apparatus. InDMA, when fine particles in an aerosol are classified, target particlesare first charged. The charged target fine particles are next applied anelectrostatic field. The classification is performed using that themobility of a particle in a medium gas is different depending on theparticle size (diameter). The details for DMA are described, forexample, in Journal of Aerosol Science, Vol.28, No.2, pp.193 to 206,1997.

The following next describes the Particle Beam Mass Spectrometry(hereinafter referred to as PBMS) which is the second conventionalexample for the fine particle classification apparatus. In PBMS, targetparticles are focused into a beam with an ultra-sonic velocity in aprocess where enclosed fine particles are injected from a particlesource to an ultra-high vacuum environment. The beam with theultra-sonic velocity of fine particles is next charged in an electronbeam. The charged target fine particles are then applied an electricfield in the ultra-high vacuum environment, thereby performing aclassification corresponding to a mass of a fine particle. The detailsof PBMS are described, for example, in Journal of Aerosol Science,Vol.26. No.5, pp.745 to 756, 1995.

In the first conventional example, it is necessary that an operation gaspressure in the DMA type classification apparatus be high, for which oneof the reason is that the development thereof was started in the premisethat an aerosol with an atmospheric pressure was sampled to classify.Therefore, it is considered that the operation gas pressure with morethan a range of 50 to 100 Torr be necessary even in a recent reducedpressure DMA type classification apparatus.

The classification accuracy for the DMA type classification apparatus isdetermined by the degree of Brownian diffusion of the target fineparticle in the aerosol. In detail, a great degree of Brownian diffusionmeans a great displacement by a fluctuation of the fine particle. Whenthe Brownian diffusion of the fine particle is great, it is not possibleto perform an accurate classification. Accordingly, when an inert gaswith a low gas pressure and a small mass as a medium gas in the DMA typeclassification apparatus, the degree of Brownian diffusion becomesgreat, and the degree of classification accuracy in the DMA typeclassification apparatus deteriorates. Therefore, it is desired to usean inert gas with a high gas pressure and a great mass to some degree asthe medium gas inside the DMA type classification apparatus.

On the other hand, it is necessary to lower a gas pressure inside anaerosol generation apparatus for generating an aerosol containing fineparticles at a gas phase. In order to generate nm-sized fine particles,in particular, with a particle diameter of less than 10 nm to producefunctional materials, it is desired to prepare inert background gaseswith a small mass as possible, and to make the gas pressure less than 50Torr, inside the aerosol generation apparatus. It is because when inertbackground gases with a high gas pressure and a great mass are preparedinside the aerosol generation apparatus, generated fine particles areaggregated and grown to large sizes thereof.

The thus generated fine particles are classified, and the classifiedfine particles are deposited on a substrate, thereby producing thefunctional materials. In this case, since the process for depositing thefine particles on the substrate is performed after the classificationprocess, it is necessary to flow the fine particles in the DMA typeclassification apparatus from the aerosol generating apparatus. It iseffective to use a differential pressure introduction to flow the fineparticles in the DMA type classification apparatus from the aerosolgeneration apparatus. Therefore, it is necessary to lower a pressureinside the DMA type classification apparatus than that inside theaerosol generation apparatus.

However, as described above, it is desired that the gas pressure insidethe DMA type classification apparatus be high to improve theclassification accuracy. There is thus a problem that it is difficult toimprove the classification accuracy in the method of introducing theaerosol from the aerosol generation apparatus to the DMA classificationapparatus using the pressure difference.

On the contrary, in the second conventional example, since the inside ofthe PBMS type classification apparatus is set to a high vacuum, thepressure inside the PBMS type classification apparatus is lower thanthat inside the aerosol generation apparatus.

However, in order to classify the fine particles with a diameter ofseveral nm without lowering the yield in the PBMS type classificationapparatus, aerodynamic lenses are needed to focus fine particles into abeam in the process that the fine particles are injected from a source.It is very difficult to design the aerodynamic lenses with a high yieldand a low dispersion of the kinetic energy. Further, it is necessarythat the electric grounding of walls of a vacuum chamber in the PBMStype classification apparatus be set at a level equal to or less than0.1 volt (V) over the entire apparatus in order to keep a size of thePBMS type classification apparatus within a size range for practicaluse. There is thus another problem that the production of the PBMS typeclassification apparatus is very difficult.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a fine-particleclassification apparatus capable of introducing an aerosol inside thefine-particle classification apparatus with a total pressure equal to orhigher than that inside the aerosol generation apparatus, andclassifying fine particles from the introduced aerosol.

The main subject of the present invention is to increase a carrier gasvelocity in a take-in section for introducing the aerosol to thefine-particle classification apparatus from the aerosol generationapparatus so as to decrease a static pressure in the take-in section,thereby introducing the aerosol inside the fine-particle classificationapparatus with a total pressure equal to or higher than that in theaerosol generation apparatus from a fine particle generating area, i.e.,aerosol generation apparatus with the total pressure equal to or lowerthan that in the fine-particle classification apparatus.

Further, it is preferable in the present invention that the take-insection made at a side of the fine-particle classification apparatushave a piping structure in which a specific carrier gas flows, and thata diameter of the introduction section be smaller than diameters ofpipes connected to the front and back portion of the take-in section,whereby the carrier gas velocity is increased locally in theintroduction section. As a result, it is possible to lower the staticpressure in the introduction section effectively.

It is further desired in the present invention to introduce, as acarrier gas or sheath gas inside the fine-particle classificationapparatus, a medium gas of which the kind is different from that of themedium gas used in the aerosol generation apparatus, in particular, themedium gas with a mass greater than that of the medium gas used in theaerosol generation apparatus.

It is thus possible to lower the static pressure in the introductionsection further effectively. As a result, it is possible to introducethe aerosol to the fine particle classification apparatus furtherefficiently. Further, by the use of the medium gas with a great mass asthe medium gas (carrier gas or sheath gas) inside the fine-particleclassification apparatus, it is possible to suppress Brownian diffusionof target particles in the fine-particle classification apparatus,thereby making it possible to improve the classification accuracy in thefine-particle classification apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the invention will appearmore fully hereinafter from a consideration of the following descriptiontaken in connection with the accompanying drawing wherein one example isillustrated by way of example, in which;

FIG. 1 is a diagram illustrating a configuration of a functionalmaterial production apparatus according to a first embodiment of thepresent invention;

FIG. 2 is a diagram illustrating a configuration of a fine-particlegeneration chamber in the functional material production apparatusillustrated FIG. in 1;

FIG. 3 is a diagram illustrating a configuration of a fine-particleclassification apparatus in the functional material production apparatusillustrated FIG. in 1;

FIG. 4 is a diagram illustrating a configuration of a deposition chamberin the functional material production apparatus illustrated FIG. in 1;

FIG. 5 is a diagram illustrating a configuration of an aerosol take-insection in the functional material production apparatus illustrated FIG.in 1;

FIG. 6A is an enlarged sectional view of a first functional materialproduced in the functional material production apparatus illustrated inFIG. 1;

FIG. 6B is an enlarged sectional view of a second functional materialproduced in the functional material production apparatus illustratedFIG. in 1;

FIG. 7 is a diagram illustrating a configuration of another example ofthe deposition section in the functional material production apparatusillustrated FIG. in 1;

FIG. 8A is a diagram illustrating a particle size distribution of fineparticles after being generated, and that of fine particles after beingclassified;

FIG. 8B is a diagram illustrating an optical gap distribution of fineparticles after being generated, and that of fine particles after beingclassified;

FIG. 9A is a diagram illustrating a particle size distribution of threekindsof Si fine-particle groups produced for multicolor (three primarycolors) optical functions;

FIG. 9B is a diagram illustrating a particle size distribution of threekinds of Si fine-particle groups produced for multicolor (threeprimarily colors) optical functions;

FIG. 10A is a horizontal sectional view of a fine-particleclassification apparatus according to a second embodiment of the presentinvention;

FIG. 10B is a longitudinal sectional view of the fine-particleclassification apparatus according to the second embodiment of thepresent invention; and

FIG. 11 is a diagram illustrating a time-dependency of the particleconcentration of fine particles with an initial diameter of 10 nmfloating in the gas.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

A functional material production apparatus according to the firstembodiment of the present invention is specifically explained usingaccompanying drawings. FIG. 1 illustrates a diagram of a configurationof the inside of the functional material production apparatus accordingto the first embodiment.

Functional material production apparatus 100 is provided with aerosolgeneration section 101 which generates an aerosol containing fineparticles. Aerosol generation section 101 is connected with aerosolclassification section 102 by first aerosol carrying pipe 107. Aerosolclassification section 102 classifies the fine particles in the aerosolgenerated in aerosol generation section 101. Aerosol classificationsection 102 is connected with deposition section 103 with fine-particledeposition nozzle 119. Deposition section 103 deposits the fineparticles classified aerosol classification section 102.

The next description explains aerosol generation section 101. Aerosolgeneration section 101 is provided with fine-particle generation chamber104. Fine-particle generation chamber 104 functions as a chamber foractually generating the aerosol containing fine particles. Provided atthe bottom of fine-particle generation chamber 104 is vacuum evacuationsystem 105 which reduces a pressure inside fine-particle generationchamber 104. Provided at a side wall of fine-particle generation chamber104 is introduction window 106. By the use of introduction window 106,it is possible to introduce a pulse laser beam radiated from a lightsource toward a solid target which is not shown in the figure butprovided inside fine-particle generation chamber 104. Provided at anupper portion in fine-particle generation chamber 104 is first aerosolcarrying pipe 107. The aerosol ejected from the solid target is suppliedto aerosol classification section 102 through first aerosol carryingpipe 107.

An end of first aerosol carrying pipe 107 is extended to a portion wherethe solid target is placed in fine-particle generation section chamber104. Provided at a tip of first aerosol carrying pipe is an aerosolcollection inlet which is not shown in the figure. The aerosolcollection inlet collects the aerosol generated in fine-particlegeneration chamber 104.

As vacuum evacuation system 105, turbo molecular pump 108 is connectedwith fine-particle generation chamber 104. Turbo molecular pump 108 isconnected with rotary pump 109.

Dry pump 110 is connected to an upper portion of fine-particlegeneration chamber 104. When an ambient inert gas is introduced insidefine-particle generation section 104, dry pump 110 differential-exhauststhe gas, and sets the ambient inert gas pressure at a constant value(about several to 100 Torr). Fine-particle generation chamber 104 isfurther connected with mass flow controller 111. Mass flow controller111 controls a flow rate of the ambient inert gas to be introducedinside fine-particle generation chamber 104.

In fine-particle generation chamber 104 with the configuration asdescribed above, after the solid target is first placed, the pressureinside is reduced by vacuum evacuation system 105, and then the ambientinert gas is introduced. Next, dry pump 110 differential-exhausts theambient inert gas, and sets the ambient inert gas pressure at a constantvalue (about several to 10.0 Torr). Under such a condition, the pulselaser beam radiated from the light source being present outsidefine-particle generation chamber 104 is introduced into fine-particlegeneration chamber 104 through introduction window 106 to irradiate thesolid target. By irradiating the solid target with the pulse laser,atoms, ions and clusters are ejected from a surface of the excited solidtarget. The ejected species are collided and aggregated together, andthen grown to fine particles in the gas phase, while repeatingcollisions to each other and also with molecules (atoms) of the ambientgas, thus generating an aerosol. The generated aerosol is collected fromthe aerosol collection inlet of first aerosol carrying pipe 107, andtransferred to aerosol classification section 102 through first aerosolcarrying pipe 107.

The next description explains aerosol classification section 102.Aerosol classification section 102 has aerosol take-in apparatus 113 ata position connected with aerosol generation section 101. Aerosoltake-in apparatus 113 introduces the aerosol generated in aerosolgeneration section 101 through aerosol carrying pipe. Aerosolclassification section 102 further has fine-particle classificationapparatus 112 at a position connected with aerosol take-in apparatus113. Fine-particle classification apparatus 112 classifies the fineparticles from the aerosol introduced from aerosol take-in apparatus113. Aerosol take-in apparatus 113 uses a carrier gas with an adequatevelocity to introduce the aerosol generated in aerosol generationsection 101 into fine-particle classification apparatus 112 using apressure difference.

Aerosol take-in apparatus 113 is connected with another end of firstaerosol carrying pipe 107. In the middle of aerosol take-in apparatus113, aerosol take-in section 115 is provided at a position connectedwith first aerosol carrying pipe 107. Aerosol take-in section 115introduces the aerosol supplied from aerosol generation section 104.First aerosol carrying pipe 107 is connected to the middle portion ofaerosol take-in section 115.

An end of aerosol take-in section 115 is connected with carrier gaspiping 116. The other end of carrier gas pipe is provided with carriergas introduction inlet 118 for supplying a carrier gas toward aerosoltake-in section 115. The carrier gas has a function for carrying theaerosol introduced into aerosol take-in section 115 to fine-particleclassification apparatus 112.

Another end of aerosol take-in section 115, which is the opposite end tocarrier gas piping 116, is connected with second aerosol carrying pipe114 for supplying the aerosol introduced into aerosol introductionsection 115 to fine-particle classification apparatus 112. Aerosoltake-in section 115, carrier gas piping 116 and second aerosol carryingpipe 114 are all structured in the form of pipes. The diameter ofaerosol take-in section 115 is designed to be smaller than that ofsecond aerosol carrying pipe 114 and that of carrier gas piping 116.

In other words, carrier gas piping 116 and aerosol take-in section 115are provided to supply the carrier gas to fine-particle classificationapparatus 112 without changing a flow direction of the carrier gas.First aerosol carrying pipe 107 is connected almost vertically to thedirection where carrier gas piping 116 and aerosol take-in section 115are connected. First aerosol carrying pipe 107 is provided to supply theaerosol generated in aerosol generation section 101 to a flow of thecarrier gas flowing in carrier gas piping 116 and aerosol take-insection 115. The diameter of an area where the aerosol joins the flow ofthe carrier gas in aerosol take-in section 115 is smaller than that ofcarrier gas piping 116 which is present at an upper stream portion thanthe portion where the aerosol joins the stream of the carrier gas.

Second aerosol carrying pipe 114 is provided with valve 125 beingpresent between aerosol take-in apparatus 113 and fine-particleclassification apparatus 112. Ionization chamber 117 for ionizing theaerosol is provided between aerosol take-in apparatus 113 andfine-particle classification apparatus 112, and at a side which iscloser to fine-particle classification apparatus 112 than valve 125.Inside ionization chamber 117, americium (Am) that is one of radioactiveisotopes is placed to charge the aerosol passing therein. Further inionization chamber 117, the fine particles are charged with ahigh-density ultraviolet light source such as an ArF excimer laser witha wavelength of 193 nm, thereby making it possible to charge the fineparticles with a monopole with high efficiency. It is thereby possibleto improve the yield of classified particles. In addition, although theArF excimer laser is used in this embodiment, it may be possible to usean excimer lamp and Deep Ultra Violet (DUV) lamp as an ultraviolet lightsource.

Fine-particle classification apparatus 112 is next explained.Fine-particle classification apparatus 112 is composed of adouble-cylinder type DMA fine-particle classification apparatus.Fine-particle classification apparatus 112 is provided with mass flowcontroller 127. Mass flow controller 127 controls a flow rate of thesheath gas which is indispensable when the fine particles are classifiedfrom the aerosol and introduced inside fine-particle classificationapparatus 112.

Mass flow controller 127 is connected with a sheath gas carrying pipefor carrying the sheath gas inside fine-particle classificationapparatus 112. Provided at a right wall of fine-particle classificationapparatus 112 is sheath gas differential-exhaustion system 126 forexhausting the sheath gas inside fine-particle classification apparatus112. Sheath gas differential-exhaustion system 126 is primarily composedof a rotary pump connected to a large-sized mechanical booster pump.Provided at a bottom of fine-particle classification apparatus 112 isfine-particle deposition nozzle 119 for carrying the carrier gas with aconstant mass flow rate Q_(a) (for example, 11/min. at standardconditions) containing the fine particles classified to have a uniformdiameter in fine-particle classification apparatus 112, and injectingsuch a carrier gas inside deposition section 103.

aerosol classification section 102 with the configuration as describedabove, the aerosol supplied to aerosol classification section 102through first aerosol carrying pipe 107 is introduced to aerosol take-insection 115 in aerosol take-in apparatus 113. The introduced aerosol issupplied to fine-particle classification apparatus 112 through secondaerosol carrying pipe 114 by the carrier gas introduced from carrier gasintroduction inlet 118. The aerosol is ionized in ionization chamber 117on the way to be supplied to fine-particle classification apparatus 112.The fine particles contained in the aerosol supplied to fine-particleclassification apparatus 112 are classified to particles with a uniformdiameter, and carried to deposition section 103 with the carrier gaswith the constant mass flow rate Q_(a).

Deposition section 103 is next explained. Deposition section 103 isprovided with deposition chamber 121 for depositing the classified fineparticles. The upper portion of deposition chamber 121 is connected tofine-particle classification apparatus 112 through fine-particledeposition nozzle 119. Provided at a left side surface of depositionchamber 121 is laser beam introduction window 120 to introduce anexcimer laser beam inside deposition chamber 121. By the use of thelaser beam introduction window, it is possible to introduce the excimerlaser beam to a transparent medium target, which is not shown in thefigure, but prepared inside deposition chamber 121. Provided at a leftside portion of deposition chamber 121 is ultra-high vacuum evacuationsystem 122 for evacuating deposition chamber 121 to be ultra-high vacuumof less than 1×10⁻⁷ Torr prior to the production of an opticalfunctional element. Further provided at the left side portion ofdeposition chamber 121 is carrier gas differential-exhaustion system 123which performs the differential-exhaustion of the carrier gas to holdthe pressure inside deposition chamber 121 at a constant pressure P2(for example, 2.0 Torr).

Deposition chamber 121 is provided with minute-ampere meter 124 whichmeasures as a current a transfer of charged fine particles (electrontransfer) carried out when the classified charged fine particles aredeposited on a deposition substrate in deposition chamber 121.

The carrier gas is carried inside deposition section 103 configured asdescribed above. The carrier gas has a constant mass flow rate Qa andcontains the fine particles with a uniform diameter classified infine-particle classification apparatus 112. In deposition chamber 121,the classified fine particles supplied from fine-particle classificationapparatus 112 are deposited, thereby producing a functional material.

Fine-particle generation chamber 104 according to the first embodimentis next explained specifically using FIG. 2. FIG. 2 is a configurationdiagram of the fine-particle generation chamber according to the firstembodiment.

Gas introduction system 209 is provided at a left side wall offine-particle generation chamber 104. Mass flow controller 111 isprovided at an end of gas introduction system 209. Mass flow controller111 is set to introduce an ambient inert gas 201 inside fine-particlegeneration chamber 104 with the constant mass flow rate Qa. Mass flowcontroller 111 is connected to ambient inert gas introduction pipe 203which is extended to a direction for the inside of fine-particlegeneration chamber 104 almost vertically to mass flow controller 111.Ambient inert gas introduction pipe 203 is connected to ambient inertgas injection pipe 210 which is bent almost vertically at a portionclosed to the side surface inside fine-particle generation chamber 104.Two ambient inert gas injection outlets 211 and 212 are formed onambient inert gas injection pipe 210. Ambient inert gas injectionoutlets 211 and 212 are provided with semiconductor target 205, which isa solid target described later, between with almost equal distancestherefrom. Thus, the ambient inert gas forms symmetry flows tosemiconductor target 205.

Introduction window 106 is provided at a side surface next to thesurface with gas introduction system 209 in fine-particle generationchamber 104. Introduction window 106 is used to introduce pulse laserbeam 204 to the semiconductor target inside fine-particle generationchamber 104. Converging lens 202 is provided outside fine-particlegeneration chamber 104 near introduction window 106 to converge pulselaser beam 204. Pulse laser beam 204 converged by converging lens 202 isintroduced into fine-particle generation chamber 104 throughintroduction window 106.

Semiconductor target 205 is placed at a position which is almost centerof the inside of fine-particle generation chamber 104 and a little closeto gas introduction system 209. Semiconductor target 205 is a solidtarget which is a base material to generate fine particles.

Semiconductor target 205 is fixed to a target holder 206 which has arotation structure. Target holder 206 is placed at a position so thatsemiconductor target 205 is irradiated by pulse laser beam 204 which isintroduced inside fine-particle generation chamber 104. Semiconductortarget 205 is excited by pulse laser beam 204 (for example, the secondharmonic wave of Nd-YAG laser with a wavelength of 532 nm) introducedinto fine-particle generation. chamber 104. Excited semiconductor target205 forms ablation plume 207. Species, which are ejected from a surfaceof semiconductor target 205 and grown to fine particles in theneighborhood outside ablation plume 207, are introduced intofine-particle take-in pipe 208.

Fine-particle take-in pipe 208 is placed near ablation plume 207 towarda growing direction of ablation plume 207, so that the fine particles inthe neighborhood of ablation plume 207 is easily introduced intofine-particle take-in pipe 208. Fine-particle take-in pipe 208 isconnected to first aerosol carrying pipe 107. The fine particlesintroduced into fine-particle take-in pipe 208 are supplied to firstaerosol carrying pipe 107, and then supplied to aerosol take-inapparatus 113.

Fine-particle classification apparatus 112 according to the firstembodiment is next explained using FIG. 3. FIG. 3 is a configurationdiagram of the fine-particle classification apparatus according to thefirst embodiment.

Fine-particle classification apparatus 112 adopts a double-cylinder typeDMA fine-particle classification method. Fine-particle classificationapparatus 112 is provided with outer cylinder 301 having thecylinder-like form as a main body of the apparatus. Inner cylinder 302is provided inside outer cylinder 301. The central axis of outercylinder 301 and that of inner cylinder 302 are placed at almost thesame position. In other words, outer cylinder 301 and inner cylinder 302have the common central axis. Second aerosol carrying pipe 114previously described is connected to the left portion of fine-particleclassification apparatus 112.

Outer cylinder 301 has the cylinder-like form of which an upstreamportion (rear end portion: hereinafter, a front portion in the directionof the flow of the aerosol is referred to as a top or front portion, andan inverse portion is referred to as a rear portion) and a top end areopened. Sheath gas introduction inlet 303 is provided at the upstreamportion. The diameter of sheath gas introduction inlet 303 becomessmaller from outer cylinder 301 as a base, making a step-like form.Filter mesh 313 is provided inside sheath gas introduction inlet 303.The sheath gas is flown to a space between outer cylinder 301 and innercylinder 302 (which is classification region 312 in the narrow sense).At this point, by the use of filter mesh 313, the sheath gas can belaminar flow effectively in classification region 312 insidefine-particle classification apparatus 112.

Passes 304 a and 304 b are formed inside outer cylinder 301 in anintermediate portion in a longitudinal direction thereof. Passes 304 aand 304 ba are composed of spaces formed between outer cylinder 301 andinner cylinder 302. Sheath gas outlets 305 a and 305 b are respectivelyprovided at the top portions of passes 304 a and 305 b. Aerosolinjection slits 306 a and 306 b are provided in the form of circularrings at a side surface in an intermediate portion of outer cylinder 301in the longitudinal direction thereof. Each of aerosol injection slits306 a and 306 b is composed of a fine space linking between the outsideand inside of outer cylinder 301.

Inner cylinder 302 is composed of a cylinder-like body with a diametersmaller than that of outer cylinder 301. The upstream portion of innercylinder 302 is closed. On the other hand, the top end portion of innercylinder 302 has an opened cap structure. Further, aerosol take-in slits307 a and 307 b are formed in the form of circular rings at a sidesurface close to the top portion in the inner cylinder 302. Aerosoltake-in slits 307 a and 307 b are respectively composed of fine spaceslinking between the inside of inner cylinder 302, and passes 304 a and304 b.

The top end portion of inner cylinder 302 is connected to aerosolextraction pipe 308 being extended from positions of aerosol take-inslits 307 a and 307 b to the top end portion. Formed at the top endportion of aerosol extraction pipe 308 is aerosol extraction outlet 309from which the classified aerosol is extracted.

Second aerosol carrying pipe 114 is branched to a plurality of branchpipes 114 a and 114 b (two FIG. in 1) in fine-particle classificationapparatus 112. Branch pipes 114 a and 114 b are branched in the symmetryforms to the common axis of double-cylinder structure of fine-particleclassification apparatus 112. The top ends of branch pipes 114 a and 114b are respectively connected to aerosol injection slits 306 a and 306 b,which are formed at a side surface of outer cylinder 301, from theoutside of outer cylinder 301. Further, sheath gas exhaustion outlets305 a and 305 b are connected to fine-particle classification apparatus112 in the symmetry forms to the common axis of double-cylinderstructure in the similar manner with second aerosol carrying pipe 114.

Cathode high-voltage electrodes 310 a and 310 b are attached inclassification region 312 on an outer wall of inner cylinder 302.Grounding electrodes 311 a and 311 b are attached in classificationregion 312 on an inner wall of outer cylinder 301. A radialelectrostatic field is formed around the common central axis by cathodehigh-voltage electrodes 310 a and 310 b, and grounding electrodes 311 aand 311 b.

A configuration of deposition section 103 is next explained specificallyusing FIG. 4. FIG. 4 is a configuration diagram of the depositionchamber according to the first embodiment.

Deposition section 103 is provided with deposition chamber 121.Fine-particle deposition nozzle 119 is provided at an upper portion on aside surface of deposition chamber 121. Fine-particle deposition nozzle119 injects the carrier gas inside deposition chamber 121. The carriergas has the constant mass flow rate Qa and contains the fine particleswith a uniform diameter classified in fine-particle classificationapparatus 112.

Laser beam introduction window 120 is provided at a position, which issymmetrical to fine-particle deposition nozzle 119 around a center ofdeposition chamber 121, in deposition chamber 121 to introduce excimerlaser beam 405. Mirror 404 is provided near laser beam introductionwindow 120 outside deposition chamber 121 to change a running directionof excimer laser beam 405 by 90 degrees. Converging lens 403 is providednear mirror 404 to converge excimer laser beam 405.

Excimer laser beam 405 converged by converging lens 403, of which thedirection is changed by 90 degrees with mirror 404, is introduced insidedeposition chamber 121 through laser beam introduction window 120.Excimer laser beam 405 introduced inside deposition chamber 121 reachestransparent medium target 408.

Transparent medium target 408 is fixed to a target drive exchangemechanism 406 which carries out the drive and exchange of the target.Target drive exchange mechanism 406 is placed at a position arranged sothat introduced excimer laser beam 405 irradiates transparent mediumtarget 408. Specifically, target drive exchange mechanism 406 isprovided near an upper portion on a side surface on the opposite side ofthe other side surface, on which fine-particle deposition nozzle 119 isprovided, in deposition chamber 121. Transparent electrode materialtarget 409, which is another transparent medium target, is also fixed totarget drive exchange mechanism 406.

Transparent medium target 408 is excited by excimer laser beam 405 andforms ablation plume 407. Transparent medium target 408 and transparentelectrode material target 409 are placed in such a manner that a growingdirection of ablation plume 407 goes toward deposition substrate 402.

Deposition substrate 402, on which fine particles, transparent media andtransparent electrodes are deposited, is placed at almost the center ofdeposition chamber 121. Deposition substrate 402 is fixed to depositionsubstrate holder 401.

Further, ultra-high vacuum evacuation system 122 is provided at a sideportion at which fine-particle deposition nozzle 119 is provided.Ultra-high vacuum evacuation system 122 evacuates deposition chamber 121to be ultra-high vacuum of less than 1×10⁻⁷ Torr prior to the productionof optical functional element. Carrier gas differential-exhaustionsystem 123 is provided at another side portion under depositionsubstrate 402 in deposition chamber 121. Carrier gasdifferential-exhaustion system 123 performs the differential exhaustionof the carrier gas to hold the pressure inside deposition chamber 121 ata constant pressure P2 (for example, 2.0 Torr).

Minute-ampere meter 124 is provided at a bottom of deposition chamber121, and measures a transfer of charged particles carried out when theclassified charged fine particles are deposited on deposition substrate402 in deposition chamber 121. Minute-ampere meter 124 electricallydetects the fine particles subjected to the classification to have auniform diameter in fine-particle classification. Minute-ampere meter124 also measures a diameter of classified fine particle and aconcentration distribution thereof. Specifically, minute-ampere meter124 measures such a transfer of fine particles as a current.

Operations in the functional material production apparatus according tothe first embodiment are next explained specifically using FIG. 1 toFIG. 5.

The generation method of nm-sized fine particles in the first embodimentis first explained. In fine-particle generation chamber 104,semiconductor target 205 with high purity semiconductor such as silicon(Si) and germanium (Ge) is irradiated with converged pulse laser beam204, whereby ions, atoms and clusters are ablated from a surface ofsemiconductor target 205. In fine-particle generation chamber 104, suchablated ions, atoms and clusters are condensed in a physical vapor phasein which inert gases such as helium (He) are filled, thereby generatingfine-particles.

At this point, the size distribution of the generated fine particlesvaries depending on species of target materials, pulse laser irradiationconditions such as a wavelength, pulse width and energy density, inertgas pressure, and a distance and direction from the target.

What provides the most effect on the particle size distribution is thepressure of an inert gas. In the case where Si is used as asemiconductor solid material, and He is used as an inert gas, so-callednm-sized fine particles with diameters of several nm to several tens nmequal to or less than 50 nm are formed when the gas pressure almostranges from 3 to 20 Torr.

Fine-particle generation chamber 104 is composed of SUS 304 alloysubjected to electrolytic polishing to be correspondent to ultra-highvacuum conditions. It is because nm-sized fine particles with a largenumber of surface exposed atoms (for example, in fine particles with adiameter of 5 nm, 40% of atoms are surface exposed atoms) are verysensitive to oxidation and impurity contamination. Further, used as eachvalve and flange connected to fine-particle generation chamber 104 is anultra-high vacuum correspondent product capable of being baked at 200°C.

Further, the generation method of nm-sized fine particles according tothe first embodiment is specifically explained. First, prior to thenm-sized fine-particle generation process, valve 125 illustrated in FIG.1 is closed to eliminate the effects of damage and contamination. Next,fine-particle generation chamber 104 is evacuated using turbo molecularpump 108 as a main pump and rotary pump 22 as a backing pump. Thus, asthe degree of achieved vacuum inside fine-particle generation chamber104, the order of 10⁻¹⁰ Torr is achieved. After the inside offine-particle generation chamber 104 is evacuated to the ultra-highvacuum, vacuum evacuation system 105 is closed.

At the same time as the aforementioned evacuation, fine-particleclassification apparatus 112 and deposition chamber 121 are bothevacuated to ultra-high vacuum of less than 1×10⁻⁷ Torr with ultra-highvacuum evacuation system 122 composed of mainly turbo molecular pump.After fine-particle classification apparatus 112 and deposition chamber121 are both evacuated, ultra-high vacuum evacuation system 122 isclosed.

Next, when nm-sized fine particles are generated, He gas with highpurity for semiconductor process (the purity thereof is more than99.9999%) is introduced inside fine-particle generation chamber 104 witha constant flow rate of 200 sccm through mass flow controller 111. Usedas mass flow controller 111 and gas introduction system 209 for the Hegas with high purity for semiconductor process are high-puritycorrespondent products with EP grade. In this case, the inside offine-particle generation chamber 104 is differential-exhausted with drypump 110 without using turbo molecular pump 108, so that the pressureinside fine-particle generation chamber 104 is held at a constant Hebackground gas pressure of 10.0 Torr.

In the reduced pressure He background gases as described above,semiconductor target 205 is fixed to target holder 206 in fine-particlegeneration chamber 104, and rotates with an angle velocity of 8 rpm(rotations/min). The pulse laser beam, which is introduced through laserbeam introduction window 106 made of quarts, is converged and irradiatedon semiconductor target 205, whereby the ablation occurs on the surfaceof semiconductor target 205.

Used as semiconductor target 205 is a high-purity Si single crystallinesubstrate (crystal orientation: (001); specific resistance: 10 Ω·cm). Aspulse laser beam 204 to be converged and irradiated, the second harmonicwave of Q-switch Nd:YAG laser (wavelength: 532 nm; pulse energy: 10 mJ;pulse width: 40 ns; repetition rate: 10 Hz) is used, and converged andirradiated so that the energy density thereof becomes 10 J/cm² on thesurface of semiconductor target 205.

The surface of semiconductor target 205 is excited by converged pulselaser beam 204. The ablation reaction is thereby generated onsemiconductor target 205, whereby spontaneous oxide films formed on thesurface semiconductor target 205 and impurities adhered thereon such asmetal and/or carbon compounds are completely removed. Thereafter,differential-exhaustion system is closed. At this point, the oscillationof pulse laser beam 204 is stopped.

As described above, the natural oxide films formed on the surface ofsemiconductor target 205 are completely removed. It is thus possible toeliminate the effects of oxide films that are impurities forsemiconductor fine particles and metal and carbon compounds adhered onthe surface of semiconductor target 205, which have the possibility ofcontaminating to the semiconductor fine particles.

Next, valve 125 illustrated in FIG. 1 is opened, and the carrier gas isintroduced to fine-particle classification chamber 112 and depositionchamber 121 with the constant mass flow rate Qa. At the same time, thesheath gas is introduced to fine-particle classification apparatus 112with the mass flow rate Q_(c) (51/min. at standard conditions) using themass flow controller 127.

At this point, carrier gas differential-exhaustion system 123 in FIG. 1is opened, and the carrier gas is exhausted with the constant mass flowrate Qa to hold the pressure inside deposition chamber 121 the aconstant pressure P2 (for example, 2.0 Torr). At the same time as theaforementioned operation, sheath gas differential-exhaustion system 126in FIG. 1 is opened, and the sheath is exhausted with the constant massflow rate Q_(c). At this point, the pressure inside fine-particlegeneration chamber 104 and the pressure inside deposition chamber 121are respectively held at the constant pressure P1 (for example, 5.0Torr) and the constant pressure P2.

Si species such ions, atoms and clusters ablated (ejected) from thesurface of semiconductor target 205 repeat collisions with atoms of theambient He gas, and thus dissipate the kinetic energy of initialejection to the ambient He gas, facilitating collision of Si species. Asa result, the aggregation of ablated (ejected) Si species in thephysical vapor phase, i.e., the generation of nm-sized fine particles iscarried out.

At this time, the size distribution of the generated nm-sized fineparticles varies depending on species of target material, pulse laserirradiation conditions such as a wavelength, pulse width, and energydensity, a distance and direction from the target, and ambient inert gaspressure.

As described previously, what provides the most effect on the particlesize distribution is the pressure of ambient inert gas. When the ambientinert gas pressure is less than a threshold, the generation of nm-sizedfine particles in the gas phase is rapidly suppressed. Then, the mostpart of ejected Si species is condensed on the deposition substrate asan amorphous Si film.

The threshold is in a range of about 3 to 5 Torr in the case where Siand He are used as materials, and a Q-switch laser with a pulse width ofseveral to several tens ns is used as a laser. When the ambient inertgas pressure exceeds this threshold and becomes excessively high, theaggregation of nm-sized fine particles rapidly occurs. As a result, fineparticles with apparent diameters of more than 20 nm are generated.Further, the particles with apparent diameters of more than 20 nm areaggregated to form particles like grape bunches, and a large number ofsuch particles are observed. It is because the confinement effect(confinement effect of plume) of ejected Si species by ambient He gasbecomes remarkable, whereby the spatial density of ejected Si speciesare excessively increased.

Therefore, in the first embodiment, 10.0 Torr is set as the ambient Hegas pressure as a low value as possible for causing the generation ofnm-sized fine particles. Further, there is a tendency that the growth offine particles is facilitated as the distance from the surface ofsemiconductor target 205 becomes longer. Accordingly, in the firstembodiment, the aerosol collection inlet of fine-particle take-in pipe208 is placed at a position with a height of 2.0 cm vertically above thesurface of semiconductor target 205.

Thus, the nm-sized fine particles generated in the gas phase areextracted as an aerosol with the ambient He gas. As a result, thekinetic energies of the nm-sized fine particles generated in the gasphase are dissipated and stayed in the gas phase, whereby the generationof large-sized particles caused by unnecessary aggregation issuppressed. The aerosol containing the collected Si nm-sized fineparticles with He gas as the medium gas is flown to aerosol take-insection 115 in aerosol classification section 102 through first aerosolcarrying pipe 107.

In the first embodiment, the total pressure of aerosol take-in section113 configured at the side of aerosol classification section 102 is setat a value equal to or more than the total pressure of aerosolgeneration section 101.

It is because the classification accuracy in fine-particleclassification apparatus 112 is determined by the degree of Browniandiffusion of target fine particles in the aerosol. Specifically, when aninert gas with a low gas pressure and a low mass is used as the mediumgas inside fine-particle classification apparatus 112, the Browniandiffusion of the target particles in the aerosol becomes prominent,resulting in a tendency that the classification accuracy in DMAdeteriorates. Therefore, it is desired that an inert gas with a high gaspressure and a large mass to some degree be used as the medium gasinside fine-particle classification apparatus 112. For this reason, itis necessary to make the total pressure inside fine-particleclassification apparatus 112 high. Specifically, it is considered thatas the total pressure inside fine-particle classification apparatus 112,the operation pressure more than 50 to 100 Torr be necessary. Further,as the total pressure inside fine-particle classification apparatus 112is increased, that of aerosol take-in section 113 is also increased.

On the contrary, the pressure inside aerosol generation chamber is 10Torr.

Generally, in the case where a fluid collides with a substance, thefluid flows along the substance after colliding with the substance. Forexample, when a gas is collided with a one end of the substance, the gasfirst collides with a surface of the substance which is vertical to theflow of the gas, and then flows along the surface of the substanceparallel to the flow of the gas. In this case, the total pressure isapplied to the surface of the substance which is vertical to the flow ofthe gas (a pressure applied to the surface of the substance which isvertical to the flow of the gas in the direction parallel to the flow ofthe gas), and the static pressure is applied to the surface of thesubstance which is parallel to the flow of the gas (a pressure appliedto the surface of the substance which is parallel to the flow of the gasin the direction vertical to the flow of the gas). The total pressure isthe sum of the static pressure and the dynamic pressure related to thegas density and gas velocity.

As illustrated in FIG. 5, the substantial gas velocity insidefine-particle generation chamber 104 can be neglected. Further, there isa laminar flow with a gas velocity q_(t) inside aerosol take-in section115. Generally, there is a relationship between static pressure P, totalpressure P_(o), density ρ, and gas velocity q of the medium gasexpressed with the following equation (1) from Bernoulli's theorem.$\begin{matrix}{{P + \frac{\rho \quad q^{2}}{2}} = P_{0}} & (1)\end{matrix}$

Hereinafter, affix “p” denotes the inside of fine-particle generationchamber 104, and affix “t” denotes the inside of aerosol take-in section115. By adding the analysis of kinetic theory of gas molecules to theequation (1), the square of gas velocity q_(p) which is an influx gasvelocity to aerosol take-in section 115 from first aerosol carrying pipe107 can be expressed with the following equation (2). $\begin{matrix}{q_{p}^{2} = {\frac{2\gamma}{\gamma - 1}\frac{P_{op}}{\rho_{t}}\left\{ {1 - \left( \frac{P_{ot} - \frac{\rho_{t}q_{t}^{2}}{2}}{P_{op}} \right)^{{({\gamma - 1})}/\gamma}} \right\}}} & (2)\end{matrix}$

Herein, γ is a ratio of specific heat of the medium gas and determinedby a structure of gas molecule. γ of inert gases (single atom gases)such as Ar (argon) and He is 1.667 not depending on the kinds of gases.

As can be seen from the above equation (1), the static pressure isdecreased by increasing the gas velocity. Further, when the staticpressure is constant, the total pressure is increased by increasing thegas velocity.

The inventors of the present invention paid attention to this principle,and found out that it is possible to supply an aerosol from aerosolgeneration section 101 to aerosol classification section 102 insidewhich the pressure is equal to or higher than that inside aerosolgeneration section 101, by applying the principle to a structure offirst aerosol carrying pipe 107 through which the aerosol is passedwhile being carried from aerosol generation section 101 to aerosolclassification section 102.

This embodiment adopts a structure illustrated in FIG. 5 to apply theabove-mentioned principle to first aerosol carrying pipe 107. In otherwords, aerosol take-in section 115, with a longitudinal direction whichis vertical to a longitudinal direction of first aerosol carrying pipe107, is connected to first aerosol carrying pipe 107. By applying such aconfiguration, it is possible to express an effective pressure insideaerosol take-in section 115 as the static pressure (P_(t)) and theeffective pressure inside first aerosol carrying pipe 107 as the totalpressure (P_(op)) when a transfer of a gas from first aerosol carryingpipe 107 to aerosol take-in section 115 is considered. Further, the gasvelocity (q_(t)) of the carrier gas towards second aerosol carrying pipe114 from carrier gas piping 116 corresponds to the gas velocity.

Thus, in the structure illustrated in FIG. 5, it is possible tosubstantially neglect the dynamic pressure inside first aerosol carryingpipe 107. On the basis of the equation (2), it is possible to decreasethe static pressure (P_(t)) in the entrance of aerosol take-in section115 by increasing the gas velocity (q_(t)) of the carrier gas. Adecrease of the static pressure (P_(t)) in the entrance of aerosoltake-in section 115 corresponds to that the effective pressure in theentrance of aerosol take-in section 115 is lower than the effectivepressure (P_(op)) inside first aerosol carrying pipe 107, therebyenabling the differential pressure introduction. As a result, it ispossible to supply the aerosol to aerosol classification section 102from aerosol generation section 101. According to the principlepreviously described, since the gas velocity of the carrier gas can beincreased further by decreasing the diameter of aerosol take-in section115, it is possible to improve the efficiency of supplying the aerosolto aerosol classification section 102.

The principle described above originates in fluid dynamics. Therefore,when a gas with a reduced pressure is an object, it is necessary thatthe gas be in a viscous flow state. Accordingly, it is desired that thecarrier gas be in the viscous flow state. Herein, the viscous flow statemeans a state where the mean free path λ of an atom composing the gas isextremely smaller than a parameter L representing a size of a flow pass(in this case, the diameter of aerosol take-in section 115) (λ<<L). Inaddition, gases with a large diameter of an atom /molecule(corresponding to a larger mass) tend to be in the viscous flow statesince the mean free path thereof is small.

Specifically, the first embodiment adopts Ar with the total pressure of25 Torr as the carrier gas, and further adopts He with the totalpressure of 10 Torr as the aerosol medium gas for the fine-particlegeneration chamber side 104.

In this setting, when the gas velocity q_(t) in aerosol take-in section115 reaches 260 m/s, it is possible to flow the aerosol from firstaerosol carrying pipe 107 to aerosol take-in section 115. In addition,the gas velocity q_(t) in aerosol take-in section 115 has an upperlimit. The upper limit value of the gas velocity is 336 m/s. Further,the influx gas velocity q_(p) from first aerosol carrying pipe 107 toaerosol take-in section 115 also has the upper limit. The upper limitvalue of the influx gas velocity is 1680 m/s. The limit values of twokinds of gas velocities described above are determined by only the kindof gas (molecular weight and molecular structure) and temperature notwithout depending on the pressure setting. To be exact, this upper limitvalue of the gas velocity is the sound velocity.

Further, according to the equation (2), the static pressure P_(t) isdecreased by increasing the gas velocity q_(t) in aerosol take-insection 115 particularly. It is thereby clarified that the introductionof the aerosol to aerosol take-in section 115 can be facilitatedeffectively. Further, it is possible to derive the effect on the gasvelocity q_(t) provided by each of other setting parameters such asρ_(t), P_(ot), ρ_(p) and P_(op). The results are summarized in Table 1.

TABLE 1 CARRIER GAS VELOCITY q_(t) q_(t) ² CARRIER GAS DENSITY ρ_(t)ρ_(t) TOTAL PRESSURE OF CARRIER GAS p_(Ot) −P_(Ot) AEROSOL MEDIUM GASDENSITY ρ_(p) ρ_(p) ⁻¹ TOTAL PRESSURE OF AEROSOL MEDIUM GAS p_(Op)P_(Op)

In the first embodiment, the flow rate of Ar as the carrier gas is setat 2.01/min (standard condition). In introducing the aerosol, a largeamount of the flow rate is advantageous as described previously.However, as described later, the excessively increased flow rateintroduces a high ratio to the sheath gas, thereby lowering theclassification resolution. It is set to achieve the flow rate (2.01/min)with 80% of the upper limit velocity 336 m/s for the gas velocity q_(t)previously described. In this setting, it is derived that the diameterof aerosol take-in section 115 should be 2.5 mm. As carrier gas piping116, ¼ inch pipes with an inner diameter of 4.3 mm are used from theavailability of EP pipes with high cleanness and the necessity to ensureconductance over the entire piping. Therefore, aerosol take-in section115 adopts a necking structure as illustrated in FIG. 5. Herein, the gasvelocity q_(t) of the carrier gas in aerosol take-in section 115 is setat a value of 80% of the limit velocity 336 m/s. In this setting, theinflux gas velocity q_(p) in a boundary area between first aerosolcarrying pipe 107 and aerosol take-in section 115 is 338 m/s. Thus, thevalue of the influx gas velocity adequately useful in practical use isensured.

In the above-mentioned configuration, the aerosol introduced to aerosoltake-in section 115 in aerosol classification section 102 is initiallycomposed of Si nm-sized fine particles and He medium gas. Then, theaerosol is mixed with argon (Ar) which is the carrier gas introducedfrom carrier gas introduction inlet 118. Therefore, the aerosol has amixed gas of Ar and He as the medium gas, and such an aerosol is startedbeing carried to fine-particle classification apparatus 112.

Next, when the above aerosol is passed through ionization chamber 117,Si nm-sized fine particles are charged by a radioactive ray radiatedfrom radioactive isotope americium (²⁴¹ Am) placed inside ionizationchamber 117. The charging rate at this time depends on diameters ofnm-sized fine particles and the pressure(mostly, the total pressure)inside second aerosol carrying pipe 114. In the first embodiment, thepressure inside second aerosol carrying pipe 114 is assumed to rangefrom 10 to 100 Torr. Therefore, it is possible to charge Si nm-sizedfine particles with a diameter of 5 nm to monovalence with the rate ofabout 10⁻⁵.

Next, the outline of operations in fine-particle classificationapparatus 112 are explained. First, Ar gas as the sheath gas isintroduced from sheath gas introduction inlet with a flow rate of201/min. The sheath Ar gas is flown to a space between outer cylinder301 and inner cylinder 302 (which is the classification region 312 inthe narrow sense) through filter mesh 313, so that the Ar gas can becomethe laminar flow effectively. At this point, the sheath gas with theflow rate almost equal to that of the influx sheath Ar gas is exhaustedfrom sheath gas exhaustion outlets 305 a and 305 b with the rotary pump.The rotary pump is connected to the large-sized mechanical booster pump.

The medium gas is composed of the mixed gas of Ar and He. The aerosolcontaining the Si nm-sized fine particles is introduced to aerosolcarrying pipes 114 a and 114 b. Next, the aerosols introduced to aerosolcarrying pipes 114 a and 114 b are respectively passed through aerosolinjection slits 306 a and 306 b. The aerosols passed through aerosolinjection slits 306 a and 306 b are introduced to classification region312. The aerosols introduced to classification region 312 are appliedthe radial electrostatic field around the common central axis by cathodehigh-voltage electrodes 310 a and 310 b attached on the outer wall ofinner cylinder 302 and grounding electrodes 311 a and 311 b attached onthe inner wall of outer cylinder 301.

Not-charged Si nm-sized fine particles, which are introduced fromaerosol injection slits 306 a and 306 b to classification region 312,join the flow of the sheath gas with the laminar flow. Then, thenot-charged Si nm-sized fine particles are carried from aerosolinjection slits 306 a and 306 b to the directions to sheath gasexhaustion outlets 310 a and 310 b (from left to right in FIG. 3 from aviewer's point) to be exhausted from sheath gas exhaustion outlets 305 aand 305 b, respectively.

On the other hand, Si nm-sized fine particles charged in ionizationchamber 117 are deflected by the electrostatic field formed inclassification region 312. In particular, positive-charged Si nm-sizedfine particles are deflected to the inner cylinder 302 side. A portionof the charged Si nm-sized fine particles are passed through aerosoltake-in slits 307 a and 307 b, and then extracted from classifiedaerosol extraction outlet 309. The locus of charged fine particles inclassification region 312 is determined fundamentally by the mobility ofcharged fine particles in the sheath gas, carrying velocity tohorizontal direction by the sheath gas, distribution of electrostaticfield strengths and geometric shapes (such as classification length L,the diameter of inner cylinder R₁ and the diameter of outer cylinderR₂). As actual operation parameters, the kind of sheath gas, flow rateof the sheath gas, sizes of charged fine particles, and valence ofcharged fine particles determine the locus. By setting such parametersappropriately, fine particles with a specific diameter can be extracted,thereby enabling the classification of the specific fine particles fromthe aerosol.

The central value of classified particle diameters is usuallypre-determined by the horizontal-direction carrying velocity and thedesign of geometric shapes. Then, the electrostatic field strength isfinally adjusted (as a variable parameter), thereby making it possibleto select any classified particle diameter in some range. Actually, theclassification accuracy at this point has a finite width of particlesize distribution after classification due to a disorder of the sheathgas laminar flow caused by the influx of the carrier gas with a finiteamount, a finite slit width, and effects of Brownian diffusion ofnm-sized particles in the sheath gas.

In the first embodiment, as the geometric shape for the classificationregion, L is 20 mm, R₁ is 24 mm, and R₂ is 35 mm. Further, as the sheathgas, Ar gas with a flow rate of 201/min is adopted. The applied voltageis variable in a range of 1 to 200V, and the positive-charged monovalentSi nm-sized fine particles are targets. According to the aforementionedsettings, it is possible to determine the central value of diametersarbitrary in a range of 5 to 10 nm. As a result, 1.2 is achieved as thegeometric standard deviation of the size distribution of classifiedparticles.

Why Ar gas is used as the sheath gas is that Ar gas improves theresolution of classification as compared to He, in the same flow rate,because Ar gas has 1.68 times the molecular diameter σ as He and 1.13times the viscosity coefficient μ as He. Further, Ar gas has the lowestprice among inert gases. In the double-cylinder type DMA classificationapparatus, it is possible to improve the classification resolution veryeffectively by setting the molecular diameter σ and viscositycoefficient μ of the sheath gas at greater values. The reason for thiscan be explained with the following equation (3) expressing the squareof relative full width at half maximum (FWHM) of the size distributionof classified particles. The equation (3) is obtained by analyzing thebehavior of the aerosol (fine particles and medium gas: carrier gas andsheath gas) in the classification region in the double-cylinder type DMAclassification apparatus as the Brownian diffusion phenomenon on thebasis of the kinetic theory of gas molecules. $\begin{matrix}\begin{matrix}{{FWHM}^{2} = \quad {{{const}.} \times \frac{\left( {b + \frac{1}{b}} \right)\frac{R_{1}}{R_{2}}\left( {R_{1} + R_{2}} \right)({kT})^{2}}{\mu \cdot \sigma^{2} \cdot Q \cdot P \cdot d_{p}^{2}}}} \\{{b = \quad \frac{L}{R_{2} - R_{1}}},{{{const}.} \cong 2.784}}\end{matrix} & (3)\end{matrix}$

It is premised that the classification resolution is proportional to thereciprocal of the relative full width at half maximum (FWHM), and theequation (3) is used. Thus, it is possible to derive the dependency onthe classification resolution of each operation parameter such as flowrate of sheath gas Q, classification operation pressure P, andclassification operation temperature T other than the molecular diameterσ and viscosity coefficient μ of the sheath gas. The results aresummarized in Table 2, where k is the Boltzmann constant.

TABLE 2 FLOW RATE OF SHEATH GAS Q Q^(0.5) OPERATION PRESSURE ρ p^(0.5)MOLECULAR DIAMETER OF SHEATH GAS σ σ PARTICLE DIAMETER OF FINE PARTICLEd_(P) d_(p) OPERATION TEMPERATURE T T⁻¹

In the first embodiment, Ar gas with a great mass is used as the sheathgas besides He gas with a small mass that is needed in the generation ofSi nm-sized fine particles. It is intended to improve the classificationresolution by adopting a greater molecular diameter σ of the sheath gas.Further, the flow rate Q of the sheath gas is also set at a great valueas possible to be contributed on the improvement of the classificationresolution. The increase of classification operation pressure P islimited because the He gas pressure in the generation of Si nm-sizedfine particles is low (10.0 Torr). In other words, the classificationoperation pressure P is limited by the structure of aerosol take-insection 115. Further, it is effective to set the operation temperatureat a lower value to improve the classification resolution. However,since it costs much to cool the whole apparatus actually, the operationtemperature is set at a room temperature. Finally, as the diameter oftarget fine particles (d_(p)) is decreased, the classificationresolution tends to be lowered. Therefore, it is necessary to carefullydesign the DMA classification apparatus for nm-sized fine particle witha diameter of several nm, specifically, less than 5 nm.

The high-purity semiconductor fine particles classified in fine-particleclassification apparatus 112 illustrated in FIG. 3 are next carried todeposition chamber 121 illustrated in FIG. 4 along with the carrier gaswith the constant flow rate Qa through fine-particle deposition nozzle119. Then, the classified particles are collected and deposited ondeposition substrate 402. At this time, transparent medium target 408 isexcited by excimer laser beam 405. The excited transparent medium target408 is ejected by the ablation reaction. At the same time as high-puritysemiconductor fine particles are collected and deposited on depositionsubstrate 402, ejected transparent medium is collected and deposited ondeposition substrate 402.

At this point, it is possible to deposit the transparent medium underoptimal conditions by control the pressure inside deposition chamber 121to hold the constant pressure P2 using carrier gasdifferential-evacuation system 123.

By carrying out the collections and depositions of the classifiedhigh-purity semiconductor fine particles and transparent medium at thesame time, it is possible to form a structure where group IVsemiconductor fine particles 602 are dispersed in semiconductor fineparticles dispersed transparent medium layer 601 on deposition substrate402 with the surface on which lower electrode layer 606 is formed. Lowerelectrode layer 606 is formed by, for example, sputtering, on depositionsubstrate 402. Further, lower electrode layer 606 is composed of, forexample, metal silicide, and has high chemical and thermal stabilities.

In addition, in the first embodiment, the collections and depositions ofthe high-purity semiconductor fine particles and transparent medium areperformed at the same time in deposition chamber 121 illustrated in FIG.4. On the contrary, it is possible that the deposition of high-puritysemiconductor fine particles is first carried out with fine-particledeposition nozzle 119 to deposit a constant amount of high-puritysemiconductor fine particles, and that the transparent medium isdeposited on the deposition substrate, so as to form a layered structureof fine particles and transparent medium. Further, by repeating thedeposition of high-purity semiconductor fine particles and that oftransparent medium alternately a plurality of times, it is possible toform a structure, as illustrated in FIG. 6B, where group IVsemiconductor fine particles layer 603 and transparent medium layer 604are piled in the form of layers.

In addition, in the first embodiment, the structure, where group IVsemiconductor fine particles 602 are dispersed in transparent mediumlayer 601, is directly formed on deposition substrate 402. It may bealso possible to form an appropriate medium layer on depositionsubstrate 402, and to form semiconductor fine particles dispersedtransparent medium layer 601, in which group IV semiconductor fineparticles 602 are dispersed, on such a medium layer.

At the same time as the collection and deposition of high-puritysemiconductor fine particles, it is possible to perform the confirmationand control of a deposition amount of fine particles using minute-amperemeter 124. Minute-ampere meter 124 measures the transfer of chargedparticles carried out when the classified charged fine particles arecollected and deposited on the deposition substrate, as the confirmationand control of the deposition amount of fine particles.

After the collection and deposition of high-purity semiconductor fineparticles and that of transparent medium are finished, transparentmedium target 408 is exchanged with Transparent electrode materialtarget 409 using the target drive exchange mechanism 406 illustrated inFIG 4.

Transparent electrode material target 409 is excited by excimer laserbeam 405, and ejects the transparent electrode species by the ablationreaction. The ejected transparent electrode species form transparentelectrode layer 605 on semiconductor fine particles dispersedtransparent medium layer 601 or transparent medium layer 604. At thistime, the kind of ambient gas and the pressure P2 inside depositionchamber 121 are controlled to enable the transparent electrode speciesto be deposited under optimal conditions as a thin film (for, example,the ambient gas is O₂ with a purity of 99.999%, the pressure is in arange of 10 to 200 mTorr).

As described above, it is possible to form the transparent electrode tobe contacted to the optical functional element in a single apparatuswith contamination and damages reduced without exposing an active regionof the functional material to the atmosphere.

In addition, the deposition of transparent medium and transparentelectrode material are carried out by the ablation by the laser beam.However, it may be possible to carry out the deposition of transparentmedium target 408 and transparent electrode material target 409 bysputtering. When the deposition is carried out by the sputtering, it ispossible to use the technique in the conventional semiconductorapparatus, and therefore to simplify mechanism parts and optical parts.Since the sputtering is carried out in mixed background gases of Ar as amain component and O₂ as a second component with a pressure of severalTorr to several mTorr, it is possible to reduce the effects of oxidationon semiconductor materials in forming transparent electrode layer 605 inparticular. As described above, it is effective to carry out thedeposition by the sputtering.

A deposition chamber which is modified based on the first embodiment isexplained using FIG. 7. FIG. 7 is a configuration diagram of thedeposition chamber modified based on the first embodiment. In addition,in FIG. 7, the same sections as those already explained have the samesymbols to omit the explanation thereof.

As illustrated in FIG. 7, fine-particle deposition nozzle 702 isprovided at almost the center on an upper portion in deposition chamber701. The classified fine particles are entering and injected insidedeposition chamber 701 along with the carrier gas with the constant flowrate Qa from fine-particle deposition nozzle 702.

Deposition substrate 402 is placed at almost the center insidedeposition chamber 701. Deposition substrate 402 is fixed to depositionsubstrate holder 401. Therefore, an injection hole of fine-particledeposition nozzle 702 is positioned to a direction of the normal line ofdeposition substrate 402.

Transparent medium target 408 is fixed to target holder 703. Targetholder 703 performs the drive of the target with motor 704. Transparentmedium target 408 is excited by excimer laser beam 405. Excitedtransparent medium target 408 generates ablation plume 407. The targetholder 703 is placed in such a manner that the growth direction ofablation plume 407 matches the direction of the normal line ofdeposition substrate 402. Further, transparent medium target 408 is madein the form of a ring.

By thus configuring the inside of deposition chamber 701, the depositionof high-purity semiconductor fine particles and that of transparentmedium are both carried out on deposition substrate 402 from the normaldirection thereof, whereby the deposition e yields of both high-puritysemiconductor fine particles and transparent medium are improved.Further, it is possible to obtain a uniform distribution of depositedspecies composed of high-purity semiconductor fine particles andtransparent medium.

Next, FIG. 8A illustrates an example of a particle size distribution ofnm-sized Si fine particles which were actually generated using theapparatus system according to the first embodiment. The classificationand deposition conditions at that time are as follows:

Generation chamber He gas pressure:5.0 Torr; deposition chamber He gaspressure:4.5 Torr; flow rate of carrier gas:He 0.33SLM (Standardconditions, 1/min); flow rate of sheath gas:He 1.67SLM; DMAclassification region applied voltage:−2.5V; deposition substrateapplied voltage:−100V; and deposition substrate temperature:roomtemperature. The other conditions with respect to Si fine particlesgeneration such as irradiation conditions of an excited laser are allthe same as described previously in the detailed explanation for FIG. 2in the first embodiment.

In FIG. 8A, the particle size distribution (hereinafter, also referredto as size distribution) of Si fine particles immediately after beinggenerated is expressed with black circles, and that of Si fine particlesafter being classified are expressed with white histograms. The particlesize distribution of Si fine particles immediately after being generatedwas calculated based on measured values by minute-ampere meter 124 dueto incidence of charged particles at deposition substrate holder 401,while sweeping the DMA classification region applied voltage(electrostatic field strength). The particle size distribution ofclassified fine particles was obtained with an electron microscope byobserving Si fine particles deposited on substrate deposition 402 underthe fixed DMA classification region applied voltage (−2.5V).

The size distribution of the generated Si fine-particles is extremelybroad (black circles: geometric standard deviation σ_(g)=1.8). However,by performing the DMA classification for the Si fine-particles, it ispossible to obtain an extremely sharp size distribution (whitehistograms:geometric standard deviation σ_(g)=1.2). Such a sharp sizedistribution is called monodispersed diameter particles

In addition, in FIG. 8A, the average particle diameter of the Sifine-particle group immediately after being generated is 5.8 nm.Further, by maintaining the DMA classified region applied voltage at−2.5V, it is possible to obtain a smaller average particle diameter of3.8 nm after the classification.

It is known in the semiconductor from the principle in quantum mechanicsthat the energy band gap _(Eg) of a semiconductor fine particle variesas a function of the particle diameter d_(m) thereof when the particlediameters are synthesized in regions comparable to Bohr radiuses ofexcitons or de Broglie wavelengths of carriers. In other words, E_(g)increases with decreasing d_(m). In the case where the material of fineparticles is Si, it is confirmed that when d_(m) ranges from 2 to 10 nm,E_(g) varies in the visible region such as a range from 1.7 to 3.0 eV,by the analysis obtained by combining effective-mass approximation andtight-binding approximation. E_(g) is exactly a physical quantity fordetermining photon energies of optical absorption.

FIG. 8B illustrates a diagram of the distributions of E_(g)corresponding to size (d_(m)) distributions of Si fine particles beforeand after the classification in FIG. 8A. As can be seen from FIG. 8B,the center of the E_(g) distribution of Si fine-particle groupimmediately after being generated (before the classification, blackcircles) is in the near-infrared region (1.4 eV). The photon energy of1.4 eV corresponds to the diameter of 5.8 nm in FIG. 8A. On thecontrary, the center of the E_(g) distribution of Si fine-particle groupafter being classified (white histograms) is in a wavelength region forthe red portion in the visible region (1.8 eV). The photon energy of 1.8eV corresponds to the diameter of 3.8 nm in FIG. 8A. It is understoodfrom the aforementioned phenomenon that it is impossible to provide theSi fine particle group immediately after being generated with theoptical function in the visible region, but it is possible to providethe Si fine-particle group with the optical function (such as opticalabsorption and light emission) in the visible region by subjecting sucha Si fine-particle group to the DMA classification. Enabling Sifine-particle group to exhibit the optical function (such as opticalabsorption and light emission) is extremely valuable in industries.

As described above, it is possible to make fine particles be in themonodispersed state by classifying the Si fine particles immediatelyafter being generated. When the fine particles are thus in themonodispersed state, in other words, the peak is present at a specificparticle diameter in the size distribution, the energy band gapscorresponding to the diameters are also made uniform. Therefore, since alarge number of classified fine particles are present, the fineparticles emit a light strongly with a wavelength corresponding to theenergy band gap. By classifying the fine particles to the diametercorresponding to the band gap energy which is the wavelength of thevisible region, it is possible to achieve the fine particles exhibitingthe optical function in the visible region. In addition, therelationship between particle diameter and energy band gap variesdepending on materials for semiconductor because the de Brogliewavelength varies depending on the materials.

Further, it is possible to produce optical functional devices withdesired wavelengths by classifying the Si fine-particle group withdesired diameters, by using that E_(g), determining wavelengths foroptical absorption and light emission, as a function of the particlediameter d_(m) of the Si fine particles. In other words, it is possibleto produce the optical functional devices in the visible region bydepositing the classified Si fine-particles with the selectedmonodispersed diameters,on deposition substrate 402.

Using the generation-classification-deposition sequential process systemin the first embodiment, three Si fine-particle groups illustrated inFIG. 9A were produced. These Si fine-particle groups were classifiedrespectively setting the average diameter at 3.9 nm, 2.4 nm and 1.9 nm.σ_(g) of each Si fine-particle group is within 1.2. The determination ofthe average diameter of Si fine-particle group can be carried out bycontrolling the DMA classification region applied voltage. By applyingthe same analysis as in FIG. 8, three Si fine-particle groups that thecentral values in E_(g) (corresponding photon energy) distributionscorrespond to 1.91 eV, 2.25 eV and 2.76 eV (FIG. 9B). The values ofE_(g) correspond to wavelengths of 650 nm, 550 nm and 450 nm,respectively. These wavelengths are exactly for the three primarycolors, i.e., for red, green and blue. It is thus possible to producethe optical functional devices with emitting wavelengths for red, greenand blue by depositing the classified Si fine-particle groups with sucha diameter co-deposited on substrate 402, with the medium, by the pulsedlaser ablation in inert background gases.

As described above, the achievement of the optical functional elementemitting three primary colors in the visible region using Si fineparticles has an extremely great significance in optical and electronicindustries.

As described above, the first embodiment has the configuration forflowing the carrier gas with a large gas velocity to aerosol take-insection 115 to introduce the aerosol to aerosol classification section.102. Thus, the static pressure in aerosol take-in section 115 islowered. As a result, even when the total pressure in aerosol take-insection 115 configured at the side of aerosol classification section 102is set at a value equal to or higher than the total pressure in aerosolgeneration section 101, the static pressure in aerosol take-in section115 can be made lower than the total pressure in aerosol generationsection 101. Accordingly, it is possible to introduce the aerosol fromaerosol generation section 101 to aerosol classification section 102with the total pressure equal to or higher than that in aerosolgeneration section 101.

Further, in the first embodiment, the specific carrier gas is flown toaerosol take-in section 115 configured at the side of aerosolclassification section 102, and the diameter of aerosol take-in section115 is designed to be smaller than the diameters of other pipesconnected to a front portion and rear portion thereof, whereby the gasvelocity of carrier gas is locally increased in aerosol take-in section115. As a result, it is possible to lower the static pressure in aerosoltake-in section 115 at the side of aerosol classification section 102effectively without preparing a specific take-in apparatus.

Further, the first embodiment has the constitution where introduced asthe carrier gas or sheath gas inside aerosol classification section 102is the medium gas of which the kind is different from that of the mediumgas inside aerosol generation section 101, in particular, the medium gaswith a mass larger than that of the medium gas inside aerosol generationsection 101. It is thereby possible to lower the static pressure inaerosol take-in section 115 in aerosol classification section 102further effectively. As a result, it is possible to introduce theaerosol to aerosol classification section 102 more efficiently. Furthermore, since the mass of the medium gas (carrier gas or sheath gas)inside fine-particle classification apparatus 112 is heavy, it ispossible to suppress the spacial dissipation by Brownian diffusion oftarget fine particles in fine-particle classification apparatus 112,resulting in the further improved classification accuracy in aerosolclassification section 102.

In addition, in the first embodiment, when the fine particles, which aregene rated from semiconductor target 205 then classified, are collectedon deposition substrate 402, substantially at the same time, the speciesgenerated by the ablation reaction on transparent medium target 408 arecollected on deposition substrate 402. It is thereby possible todisperse the classified fine particles generated from semiconductor 205in the species composed of transparent medium target 408 to deposit. Asa result, it is possible to produce the high-purity fine particles withthe monodispersed diameter and uniform structure efficiently withcontamination and damages reduced, and to deposit such high-purity fineparticles on the substrate at the same as the deposition of thetransparent medium. Thus, it is possible to compose the form andstructure of high quality optical functional devices.

Further, in the first embodiment, it is possible to alternately deposita thin film composed of classified fine particles generated fromsemiconductor target 205 and another thin film composed of transparentmedium target 408. As a result, it is possible to produce thehigh-purity fine particles with the monodispersed diameter and uniformstructure efficiently with reducing contamination and damages, and todeposit such high-purity fine particles and the transparent mediumalternately on the substrate.

In addition, fine-particle classification apparatus 112 according to thefirst embodiment adopts the type electric mobility classificationapparatus. It is thereby possible to classify fine particles with a highyield. As a result, the high-purity fine particles with a monodisperseddiameter and uniform structure can be collected and depositedefficiency.

Further, according to the first embodiment, it is possible to hold thepressure inside fine-particle generation chamber 104 at the optimalpressure for the condensation and growing of fine particles generatedfrom semiconductor target 205. It is also possible to hold the pressureinside deposition chamber 121 at the optimal pressure for the depositionof species generated from transparent medium target 408. It is therebypossible to generate and deposit the fine particles and transparentmedium under respective optimal ambient gas pressures. Furthermore, itis possible to cause a pressure difference between aerosol generationsection 101 and deposition section 103. By the use of the generatedpressure difference, it is possible to carry the fine particles fromaerosol generation section 101 to deposition section 103 efficiently.

In addition, according to the first embodiment, it is possible toexchange transparent medium target 408 with transparent electrodematerial target 409 using target drive exchange mechanism 406 providedat deposition chamber 121. It is thereby possible to excite transparentelectrode material target 409 after depositing the species composed ofsemiconductor target 205 and transparent medium target 408. Then, it ispossible to deposit species generated by the ablation reaction caused bythe excited transparent electrode material target 409 on the speciescomposed of semiconductor target 205 and transparent medium target 508to form a transparent electrode. As a result, it is made possible toalso form the transparent electrode to be contacted to the opticalfunctional devices in a single apparatus with reducing contamination anddamages without exposing the active region of he functional functionalmaterials to the atmosphere.

Further, in the modification example on the basis of the firstembodiment, it is possible to carry out the deposition of speciescomposed of semiconductor target 205 and transparent medium target 408on the substrate from the normal direction to the substrate, therebymaking it possible to improve the yields of stacking and deposition tothe substrate of the fine particles and transparent media.

In addition, the first embodiment has ionization chamber 117 adopting acharging system for target fine particles using the radioactive isotope.Further, the charging efficiency can be improved by using a vacuumultraviolet light source to charge the fine particles in ionizationchamber 117.

In addition, in the first embodiment, the generated fine particles arecharged in the ablation plume generated by the excitation pulse laser.Therefore, it is possible to eliminate ionization chamber 117 where theradioactive isotope and vacuum ultraviolet ray source are used. Thus, itis possible to perform the miniaturization and cost reduction of theapparatus, and further to shorten the process of carrying fineparticles. As a result, it is possible to suppress the phenomena such asdeposit and aggregation of fine particles being carried.

Further, in the first embodiment, it may be possible to carry out thedeposition of transparent medium target 408 and transparent electrodematerial target 409 by sputtering. It is thus possible to use thetechnique in the conventional semiconductor apparatus, and to furthersimplify mechanical parts and optical parts.

Second Embodiment

A functional material production apparatus according to the secondembodiment of the present invention is explained. The apparatus isobtained by modifying the fine-particle classification apparatusaccording to the first embodiment to be operated in a pressure lowerthan the atmospheric pressure. In order to operate the fine-particleclassification apparatus in the pressure lower than the atmosphericpressure, it is necessary to exhaust a sheath gas inside thefine-particle classification apparatus efficiently with a highexhaustion rate.

In the second embodiment, in order to achieve the subject, it is noticedthat an increase of the cross-section area of the classification regionin the fine-particle classification apparatus is efficient. Actually, inorder to increase the cross-section area of the classification region inthe fine-particle classification apparatus, the form of the crosssection of the fine-particle classification apparatus is modified fromthe double-cylinder type to a rectangle type.

In addition, the sections and chambers in the second embodiment are thesame as in the first embodiment except the fine-particle classificationapparatus, and explanations thereof are omitted.

The fine-particle classification apparatus according to the secondembodiment is next explained using FIG. 10A and FIG. 10B. FIG. 10A andFIG. 10B are configuration diagrams of the fine-particle classificationapparatus according to the second embodiment.

Fine-particle classification apparatus 801 has the cross-section in theform of a rectangle, and is composed of outer shell portion 817 withspace portion 818 of which the form of the cross-section is nearlyrectangle. Flat portions A802 and B803 are formed in parallel to eachother on respective inner surfaces at left and right sides in outershell portion 817, being faced to each other with a constant interval R.The forms of flat portions A802 and B803 are both rectangles.

Provided at a slightly upper portion than the center in the side of flatportion A802 of outer shell portion 817 is carrier gas introductioninlet 804 for introducing the carrier gas which carries the charged fineparticles. Provided near carrier gas introduction inlet 804 at the sideof flat portion A802 of Outer shell portion 817 is carrier gas injectionoutlet 805 for injecting the introduced carrier gas to classificationregion 806.

Classification region 806 is a space with a constant interval R betweenflat portions A802 and B803 of space portion 818 inside outer shellportion 817. In addition, carrier gas injection outlet 805 is providedat a higher portion in classification region 806 of outer shell portion817.

Provided at a side surface at the side of classification region 806 atthe side of flat portion B803 of outer shell portion 817 is slit 807 forselecting fine particles with a monodispersed diameter. Provided at anouter side surface of outer shell portion 817 near slit 807 is carriergas exhaustion outlet 808 to extract the selected fine particles withthe monodispersed diameter.

In addition, metal plate 809 is provided on a side surface, at the sideof classification region 806, of outer shell portion 817. In otherwords, a portion of flat portion B803 is composed of metal plate 809.Metal plate 809 is surrounded with insulator 810 being contactedthereto, whereby metal plate 809 is completely insulated by insulator810. In addition, insulator 810 is provided to shield an inside portionof outer shell portion 817 except a portion of flat portion B803 inouter shell portion 817.

DC power supply 811 is connected to the side surface at the side of flatportion B803 in outer shell portion 817. The outer of outer shellportion 817 is grounded by DC power supply 811. Metal plate 809 isapplied a positive or negative voltage by DC power supply 811.

Filter 812 is provided at an upper stream portion than classificationregion 806 in fine-particle classification apparatus inside outer shellportion 817. Filter 812 makes the sheath gas, introduced from sheath gasintroduction inlet 813, a uniform laminar flow.

The fine particle classification operation in fine-particleclassification apparatus 801 is next explained.

Sheath gas 814 is introduced to fine-particle classification apparatus801 through sheath gas introduction inlet 813, and then passed throughfilter 812. By being passed through filter 812, the flow of sheath gas814 in fine-particle classification apparatus 801 is made uniform.

After being passed through filter 812, sheath gas 814 is passed throughclassification region 806 in a state of laminar flow, and then exhaustedfrom sheath gas exhaustion outlet 815. On the otherhand, charged fineparticles are carried by carrier gas 816, and introduced tofine-particle classification apparatus 801 from carrier gas introductioninlet 804. Carrier gas 816 introduced to fine-particle classificationapparatus 801 is injected to classification region 806 from carrier gasinjection outlet 805.

In classification region 806, the electrostatic field is applied to aspace between flat portions A802 and B803 in a direction vertical to theflow of sheath gas 814. Therefore, the fine particles injected fromcarrier gas injection outlet are carried downward, while indicating thedeflected loci in a direction from flat portion A802 to flat portion B803. The loci are the deflection corresponding to the degree of electricmobility which depends on the number of charged fine particles and thediameter of fine particles. Then, only particles reaching slit 807provided at the lower portion of flat portion B803 are extracted fromcarrier gas exhaustion outlet 808 as classified fine particles.

In order to improve the classification resolution in fine-particleclassification apparatus 801, it is necessary that the sheath gas passedthrough classification region 806 be in a laminar flow state. In orderto achieve the laminar flow state, as a form of the cross section, it isdesired to avoid a form with acute angles which tend to generatestagnation. It is further desired that the form of the cross section ofclassification region 806 be smooth curved lines as possible.Accordingly, four corners 819 a to 819 d of the cross section ofclassification region 806 in rectangle type fine-particle classificationapparatus 801 are cut to be circles. It is thereby possible to generatefurther uniform laminar flow state of sheath gas 814. As a result, it ismade possible to improve the classification resolution of fine particlesin fine-particle classification apparatus 801.

In addition, generally, an exhaustion conductance of a pipe isproportional to the square of the cross-section area of the pipe in theviscous flow area. Therefore, the cross-section area of classificationregion 806 in fine-particle classification apparatus 801 is set at avalue equal to or more than that of the sheath gas pipe at the upperstream portion than sheath gas introduction inlet 813. Thus, theconductance of classification region 806 in fine-particle classificationapparatus 801 is set at a value equal to or more than that of the sheathgas pipe at the upper stream portion than sheath gas introduction inlet813. As a result, it is possible to eliminate stagnation in sheath gas814 flown to classification region 806 through sheath gas introductioninlet 813 from the sheath gas pipe. Further, it is made possible thatsheath gas 814 passed through classification region 806 becomes thelaminar flow state.

Further, the form of the cross section of the sheath gas pipe at theupper stream portion than sheath gas introduction inlet 813 is designedto be continuously changed to the form of the cross section ofclassification region 806 in fine-particle classification apparatus 801.It is thereby possible to prevent rapid changes of the form of a sheathgas pass in front and rear portions of sheath gas introduction inlet813. As a result, it is made possible that stagnation and disorder ofthe sheath gas flow are suppressed, and that the sheath gas passedthrough classification region 806 becomes the laminar flow state. Inother words, it is made possible to achieve fine-particle classificationapparatus 801 with excellent classification performance.

In particular, when the cross-section area of classification region 806in fine-particle classification apparatus 801 is equal to that of thesheath gas pipe at the upper stream portion than sheath gas introductioninlet 813, it is important that the changes of the form of the sheathgas pass around sheath gas are made smooth and continuous in the frontand rear portions of sheath gas introduction inlet 813. The reason forthis is that making the changes of the form of the sheath gas passsmooth and continuous in the front and rear portions of sheath gasintroduction inlet 813 is extremely effective to the flow of the sheathgas keeps the laminar flow state.

In addition, in order to operate fine-particle classification apparatus801 at a pressure lower than the atmospheric pressure, it is necessaryto exhaust the sheath gas with a high exhaustion rate. Alternately, inorder to operate fine-particle classification apparatus 801 at apressure lower than the atmospheric pressure, it is necessary to exhaustthe sheath gas efficiently with sheath gas differential-exhaustionsystem 126 illustrated in FIG. 1.

To solve the above problem, in fine-particle classification apparatus801 according to the second embodiment, the form thereof is modified toa rectangle type. It is thereby achieved to obtain the fine-particleclassification apparatus in which the cross-section area ofclassification region 806 in fine-particle classification apparatus 801is decreased to a value almost equal to that of the cross-section areaof the sheath gas pipe at the upper stream portion than the sheath gasintroduction inlet. As a result, it is possible to decrease the sheathgas capacity inside fine-particle classification apparatus 801considerably. Further, the low pressure operation in fine-particleclassification apparatus 801 is achieved by exhausting the sheath gasefficiently with sheath gas differential-exhaustion system 126 composedof a small-sized vacuum pump.

Specifically, as the sheath gas pipe at the upper stream portion thansheath gas introduction inlet 813 illustrated in FIG. 10, for example, acylinder pipe with a diameter of 0.5 inch (about 12.7 mm) is used.Further, the cross-section area of classification region 806 infine-particle classification apparatus 801 is decreased to the value(about 130 mm²) almost equal to that of the cross-section area of thesheath gas cylinder pipe. Furthermore, projection length L betweencarrier gas injection outlet 805 and slit 807 is set at 20 mm. Thesheath gas capacity inside fine-particle classification apparatus 801 ismade one-two hundredth that of fine-particle classification apparatus112 according to the first embodiment. As a result, even when asmall-sized vacuum pump with a rate of 1301/min is used as a pumpcomposing sheath gas differential-exhaustion system 126, it is madepossible to operate the fine-particle classification apparatus 801 at alow pressure in a range of 20 to 50 Torr.

In addition, the four corners of the cross section, which is arectangle, of classification region 806 in fine-particle classificationapparatus 801 are cut to be circles, so that the cross section of sheathgas cylinder pipe, which is a circle, is continuously changed to thecross section of classification region 806. By thus avoiding the rapidchanges of the form of gas path in the front and rear portions of sheathgas introduction inlet, disorders in the sheath gas flow are suppressedand the laminar flow thereof is held.

The fine particles introduced to fine-particle classification apparatus801 by second aerosol carrying pipe 114 illustrated in FIG. 1 areextracted from classified aerosol extraction outlet 309. The carryingtime of fine particles spent by the detection thereof at Minute-amperemeter 124 depends on the flow rate of the carrier gas and that of thesheath gas.

Generally, fine particles floating in a gas cause the collision andaggregation thereof due to the effect of Brownian diffusion. Thediameter of the fine particles are thereby increased as time passes.Further with the aggregation of fine particles, the particleconcentration of the fine particles floating in the gas is decreased.Basically, in the case where the initial diameters of the fine particlesare uniform, the particle concentration of the fine particles isdecreased in inverse proportion to the time. In the case where theinitial particle concentration of fine particles floating in the gas islarge, the ratio of aggregation thereof is also large. As a result, thedependency of the particle concentration on the time and initialparticle concentration is expressed as that a difference between thereciprocal of the initial particle concentration and that of a particleconcentration at some time is proportional to the time.

Accordingly, when the carrying time of fine particles is long, theeffects of aggregations of fine particles cannot be eliminated. In orderto decrease the effects of such aggregations, it is considered toshorten the carrying time of fine particles, or to decrease the initialparticle concentration of fine particles. In order to shorten thecarrying time of fine particles, it is considered to increase the gasvelocities of carrier gas and sheath gas, or to shorten a distancebetween second aerosol carrying pipe 114 and minute-ampere meter 124.

In addition, the initial particle concentration of fine particles alsodepends on the generation method of fine particles. Accordingly, it iseffective to miniaturize fine-particle classification apparatus 801,further to use a small-sized pump as a vacuum pump composing sheath gasdifferential-exhaustion system 126, and to shorten the distance betweensecond aerosol carrying pipe 114 and minute-ampere meter 124.

FIG. 9 illustrates the time dependency of the particle concentration offine particles floating with the initial particle diameter of 10 nm.

As can been seen from FIG. 9, when the initial particle concentration offine particles with the initial diameter of 10 nm is 10¹² particles/m³,the time required by that the initial particle concentration becomeshalf is more than about 1.0 sec. In other words, when the time requiredby that the fine particles are carried to minute-ampere meter 124 fromsecond aerosol carrying pipe 114 is within 1.0 sec, it is possible tosuppress that the initial particle concentration of fine particles isdecreased to the half thereof. In this case, it is possible to suppressthe effects of aggregations of fine particles considerably.

Specifically, the carrying path from second aerosol carrying pipe 114 tominute-ampere meter 124 is composed of pipes with a diameter of 0.5inch. The carrying distance between second aerosol carrying pipe 114 andminute-ampere meter 124 is set to 50 cm. The flow rate of carrier gas is1SLM (1/min at 0° C. and 1 atmospheric pressure). Under theseconditions, the carrying velocity for fine particles when the operationpressure of fine-particle classification apparatus 801 is about 50 Torr(in other words, the pressure inside carrier gas pipe is about 50 Torr)is about 2.2 m/sec. Therefore, the time required by the carry of thefine particles is estimated to be about 0.23 sec. It is thus achieved toobtain fine-particle classification apparatus 801 in which the timerequired by that the particles are carried from second aerosol carryingpipe 114 to minute-ampere meter 124 is within 1.0 sec. In such andevice, it is possible to classify and detect fine particles with thediameter of 10 nm when the operation pressure in fine-particleclassification apparatus 801 is in a range of 20 to 50 Torr.

As described above, by miniaturizing fine-particle classificationapparatus 801, it is possible to provide a fine-particle classificationapparatus which is easy to carry and enables the easy attachment thereofto any kind of aerosol generation apparatus.

As described above, in fine-particle classification apparatus 801according to the second embodiment, flat portions A802 and B803 are inthe form of rectangles, so that fine-particle classification apparatus801 has classification region 806 in the form of a rectangle. As aresult, it is made possible to classify fine particles efficiently.

Further, the cross-section area of classification region 806 is madeequal to or larger than that of the pipe at the upper stream portionthan sheath gas introduction inlet 813. Thus, the cross-section area ofclassification region 806 can be decreased to a value equal to that ofthe cross-section area of the pipe at the upper stream portion thansheath gas introduction inlet 813. As a result, it is possible todecrease the sheath gas capacity inside fine-particle classificationapparatus 801. Further, it is possible to decrease the effectiveexhaustion rate and exhaustion capacity of a vacuum pump placed at adownstream portion than sheath gas exhaustion outlet 815. Furthermore,in the case where the cross-section area of classification region 806 ismade equal to that of the pipe at the upper stream portion than sheathgas introduction inlet 813, it is possible to prevent rapid changes ofconductance in front and rear portions of sheath gas introduction inlet813. Thus, it is possible to suppress stagnation from being generated inthe flow of sheath gas.

In addition, in the second embodiment, the form of the cross section ofthe sheath gas pipe at the upper stream portion than sheath gasintroduction inlet 813 is continuously changed to the form of the crosssection of classification region 806. It is thereby possible to preventthe rapid changes of the form of sheath gas path in the front and rearpotions of sheath gas introduction inlet 813. As a result, it ispossible to suppress stagnation and disorder of the sheath gas flow, andto keep the laminar flow thereof.

Further, in the second embodiment, the four corners of the cross sectionof classification region 806 are cut to be circles, thereby facilitatingthat the sheath gas being flown from the pipe in the form of a cylinderat the upper stream portion than sheath gas introduction inlet 813 keepsthe laminar flow inside fine-particle classification apparatus 801.

In addition, according to the second embodiment, it is possible to carrythe fine particles, which are generated at a pressure less than theatmospheric pressure and then ionized in ionization chamber 117, tofine-particle classification apparatus 801 with the differentialexhaustion to classify.

In addition, in the second embodiment, the operation pressure insideclassification region 806 is less than 50 Torr. It is thereby possibleto carry the fine particles, which are generated at a pressure less than50 Torr and then ionized in ionization chamber 117, to fine-particleclassification apparatus 801 with the differential exhaustion toclassify.

Further, in the second embodiment, the time required by the fineparticles being carried from second aerosol carrying pipe 114 tominute-ampere meter 124 is within 1.0 second. By thus shorting thecarrying time spent by the fine particles being introduced and thendetected, it is possible to reduce the effects of the aggregations offine particles in the carrying process.

The present invention is not limited to the above described embodiments,and various variations and modifications may be possible withoutdeparting from the scope of the present invention.

This application is based on the Japanese Patent ApplicationNo.HEI10-314297 filed on Nov. 5, 1998, entire content of which isexpressly incorporated by reference herein.

What is claimed is:
 1. A low pressure functional material productionapparatus comprising: an aerosol generation section which generates anaerosol containing fine particles by irradiating a laser beam on a firsttarget material in a low pressure background gas; an introductionsection which introduces the aerosol generated in the aerosol generationsection to a fine particle classification section; the fine particleclassification section comprising an apparatus capable of classifyingthe fine particles based on electrical mobility, which classifies thefine particles, in a sheath gas, from the aerosol, in a low pressurebackground gas; and a deposition section which receives fine particlesclassified in the fine particle classification section and receivesspecies generated by irradiating a laser beam on a second targetmaterial, and deposits the classified fine particles and the species onthe substrate, in a low pressure background gas.
 2. The apparatus ofclaim 1, wherein the introduction section introduces the aerosol to theclassification system using a carrier gas with a velocity sufficient tointroduce the aerosol into the classification section using a staticpressure differential.
 3. The apparatus of claim 1, wherein thedeposition section receives the species at substantially the same timeas collecting the classified fine particles on the substrate anddisperses the classified particles in the species.
 4. The apparatus ofclaim 1, wherein the deposition section receives the species atsubstantially the same time after collecting the classified fineparticles on the substrate and dispersing the classified particles inthe species.
 5. The apparatus of claim 1, wherein the deposition sectionfurther comprises a target exchange mechanism which exchanges the secondtarget material for a third transparent electrode target material,irradiates the third material with a laser beam to generate specieswhich are deposited on the classified fine particles and species of thesecond target material, so as to form a transparent electrode.
 6. Theapparatus of claim 1, wherein the deposition section is configured todeposit the classified fine particles and the species composed of thesecond target material from a direction normal to the substrate.
 7. Theapparatus of claim 1, wherein the classification section comprises acharging section, which electrically charges the fine particles using aradioactive isotope.
 8. The apparatus of claim 1, wherein theclassification section comprises a charging section which electricallycharges the fine particles using a vacuum ultraviolet light source. 9.The apparatus of claim 1, wherein the aerosol generation section chargesthe fine particles generated with the laser beam as a pulse laser in anablation plume caused by a pulse laser beam.
 10. The apparatus of claim1, wherein the deposition section measures an electron transfer carriedout as classified charged fine particles are deposited using an electriccurrent.
 11. The apparatus of claim 5, wherein the deposition sectioncarries out deposition of both or either of the second and third targetmaterials by sputtering.
 12. The apparatus of claim 1, wherein theoperating pressure in the classification section is less than 50 Torr.13. The apparatus of claim 1, wherein the time required to transfer thefine particles from the introduction section to the deposition sectionis within 1 second.
 14. The apparatus of claim 1, wherein the density ofthe carrier gas is greater than the density of the low pressurebackground gas inside the aerosol generation section.
 15. The apparatusof claim 1, wherein a density of the sheath gas is greater than thedensity of the low pressure background gas inside the aerosol generationsection.
 16. The apparatus of claim 1, wherein the carrier gas is in aviscous flow state.